## Recurrent Herpes Simplex Virus — Most Common Site **Key Point:** Oral herpes (herpes labialis) is the most frequent site of HSV recurrence in immunocompetent hosts, accounting for >90% of all recurrent HSV episodes. ### Pathophysiology of Recurrence After primary infection, HSV establishes latency in sensory ganglia (trigeminal for oral, sacral for genital). Reactivation occurs along the same dermatome due to: - Viral replication in latent neurons - Anterograde axonal transport to skin - Local viral shedding and ulceration ### Frequency of Recurrence by Site | Site | Recurrence Frequency | Typical Triggers | |------|----------------------|------------------| | **Oral (lips/mucosa)** | **50–90% of HSV-1 infections** | Stress, UV exposure, fever, immunosuppression | | Genital | 50–90% of HSV-2 infections | Sexual stress, menstruation, immunosuppression | | Ocular | 10–20% of primary keratitis cases | Recurrent in ~25% | | Sacral | Rare in immunocompetent; common in HIV | Severe immunosuppression (CD4 <50) | **Clinical Pearl:** HSV-1 preferentially causes oral recurrences; HSV-2 causes genital recurrences. However, both can infect either site, and the pattern of recurrence follows the initial site of infection and latent ganglia involved. **High-Yield:** In immunocompetent individuals, oral HSV recurrence is 10–20 times more common than genital or disseminated disease. Sacral involvement (including sacral ganglionitis with urinary retention) is rare and should raise suspicion for immunocompromise (HIV, chemotherapy, transplant). ### Why Oral Site Is Most Common 1. **Epidemiology:** HSV-1 seroprevalence is 60–90% globally; most primary infections are oral (often asymptomatic in childhood) 2. **Trigger sensitivity:** Oral recurrences are triggered by milder stimuli (stress, sunlight) than genital recurrences 3. **Viral shedding:** Oral site has higher frequency of asymptomatic viral shedding [cite:Harrison 21e Ch 187]
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